Filament handling process and apparatus



P 1962 w. H. HENDRIX 3,055,786

FILAMENT HANDLING PROCESS AND APPARATUS Filed July 19, 1960 2 Sheets-Sheet 1 J I l5 l3 I4 i' FIGI 1y i O I L .l

24/L '4 mmonn' -nommn I3 23 2O CL D l I 4 Ag Will a 5 INVENTOR a WALTER H. HENDRIX I QM ATTORNEY Sept. 25, 1962 w. H. HENDRIX 3,055,736

FILAMENT HANDLING PROCESS AND APPARATUS Filed July 19, 1960 2 Sheets- Sheet 2 INVENTOR WALTER H. HENDRIX 3,055,786 FHLAMENT HANDLING PROCESS AND APPARATUS Walter H. Hendrix, Lugolf, S.C., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Filed July 119, 196i Ser. No. 43,893 11 Claims. (Cl. 156-158) This invention relates to a filament handling process and apparatus, and more particularly to an improved method and apparatus for joining together individual ends of thermoplastic filaments to form a continuous warp sheet.

In the preparation and utilization of filaments and yarns, it is both convenient and economical to treat a multiplicity of ends simultaneously. This is generally accomplished by treating the filament or yarn ends in the form of a warp sheet. In some instances the warp is made up of individual ends from separate packages; however, it is generally preferred to have all of the ends wound onto a common package and unwound simultaneously from that package for the next treatment. For example, a number of separate yarn ends from individual spinning cells may be wound simultaneously onto a beam and then unwound from that beam for passage through stretching apparatus.

In most instances threading or stringing up a large number of yarn ends simultaneously through treat ng apparatus, e.g., stretching apparatus, is a time-consuming and tedious task. It is, therefore, highly desirable to be able to attach the lead-in ends of a fresh beam of yarns to the run-out ends of a preceding beam. At the present time this is accomplished by separately knotting each run-out end to a lead-in end from the new beam. These knots must be tied with especial care so that the variation in tension between ends is kept to a minimum. The tyingin process is particularly difficult in the case of undrawn, solvent-laden yarns, for example acrylonitrile polymer yarns which are notoriously weak and difficult to handle. In addition, in most instances, the loose, trailing ends of filaments at the knots must be removed.

It is, therefore, an object of this invention to provide a process for simultaneously joining individual ends from one warp of yarns to the ends of a second warp of yarns. Another object is to provide a process for joining the ends of two warps of yarns in which the juncture of the yarns does not contain loose, trailing ends. A further object of this invention is to provide a process in which the joined strands are all of essentially equal length and under substantially the same tension. Still another object is to provide new and improved apparatus for joining yarns of one warp to the yarns of another warp. Other objects will be apparent from the description that follows.

The objects of this invention are accomplished by a process which comprise positioning the terminal portions of the lead-in ends of yarns of a first warp in overlapping relationship to the terminal portions of the runout ends of yarns of a second warp, applying an essentially equal tension to all the ends while maintaining the overlapping relationship along at least a portion of the yarns, applying pressure to at least a part of the overlapping portion of the ends, and thereafter heating the yarns to a heat-sealing temperature whereby they are softened and fused together. The tension on the leading and trailing portions of the yarns which protrude from the overlapped portion is controlled to cause the loose terminal portion to separate from the fused portion when the yarns soften.

In general the apparatus is comprised of a pair of pressure members having opposed flat pressure faces.

States atent A comb member is displaced on each side of the pressure members for aligning the filament ends in essentially parallel overlapping relationship in a zone between the pressure members. A tensioning means is positioned adjacent to the pressure members to receive the terminal portion of the ends and to maintain the yarns under substantially uniform tension. Suitable means for displacing the pressure members toward each other to compress the overlapping portions of the filaments are interposed between the faces. Means for heating the overlapping portions of the yarns to a heat-sealing tempera-. ture are operatively connected to at least one of the pressure members.

The present invention will be further described in conjunction with the accompanying drawings in which:

FIGURE 1 is a top plan view of the yarn-splicing apparatus of this invention;

FIGURE 2 is a side view of the apparatus hown in FIGURE 1; and

FIGURE 3 is an end view showing a section taken on line 3 -3 of FIGURE 2.

With reference to FIG. 1, a warp sheet 11 passes from guide roller 12 through guide pins 13 and 13' which are mounted on comb assembly 14. The yarns of a second warp 15 from warp beam 16 pass between guide pins 13 and 13'. Guide pins 13 and 13' are closely spaced and are arranged to maintain the yarns in essentially parallel overlapping relationship.

Referring now to FIGS. 1 and 2, the yarns pass over heater plate 17, which has a flat face and is operatively connected to a heater control assembly 18. A pressure plate 19 is positioned above heater plate 17 and is elevated and depressed by linkage 20. A pressure plate guide 21 insures proper alignment of the pressure plate when it is displaced toward and away from heater plate 17. Positioned adjacent to heater plate 17 is a suction nozzle 22;, which is adapted to permit the inward passage of air and to receive the terminal portion of the ends of the yarns of warps Ill and 15. Circular guide bars 23 are secured to frame It) to facilitate the passage of the yarns through the splicing apparatus. Guidebar 24 is positioned above nozzle 22 to aid in directing the terminal portions of the yarns into nozzle 22 prior to and during the heat-sealing steps as shown in FIGURE 2. Suction nozzle 22 is provided with a conduit 25 and a trap 26 for collecting the loose ends as they are separated from the joined yarn structures. A suitable pump '27 i attached to the suction system through conduit 28.

Referring now to FIG. 3, pressure plate 19 is provided with a thin pad 29 of a suitable insulating material which is selected to prevent sticking of the yarns thereto. Heater bar 17 is thermally insulated from frame 10' and surrounding parts by gaskets 30, 31, and 31.. Rod and spring assembly 3-2. may be adjusted to regulate the pressure on prmsure plate 1%, which in turn exerts pressure on the overlapping portions of the yarns of warp sheets 11 and E5. The terminal portions of the yarns are shown passing over the circular guide bars.

The following procedure is exemplary of the utilization of the process and apparatus of the present invention. Continuous filament yarns were prepared from a copolymer containing 94% acrylonitrile and 6% methylacrylate. Forty-eight (48) separate multifilarnent yarns were spun from a dimethylformamide solution by a dry-spinning process and were simultaneously wound onto a single beam according to the process described in the copending application of Block, US. application, Serial No. 743,325, filed June 20, 1958, now Patent No. 2,972,- 796. The yarns contained 25% dimethylformamide solvent. Three of the beams having a total of 144 ends of yarn were threaded through the pins of apparatus similar to that shown in FIG. 1, and then passed into a stretching apparatus of the type described in Kinraide U.S. Patent 2,568,920. The ends of yarn were simultaneously unwound from the beams until the beams were almost empty, at which time the runout ends of the yarn were removed from the beams and directed into suction nozzle 22 as shown in FIG. 2. Three fresh beams of yarn were then moved into position and the leading ends were placed in overlapping relationship with the runout ends between corresponding pairs of guide pins 13 and 13'. The lead-in ends were then pulled toward the end of the comb assembly and directed into suction nozzle 22 as shown in FIG. 3. The tension on each of the yarn ends was approximately equal and the yarn ends were spaced approximately As" above heater plate 17. Pressure plate 19 was then placed into position against heater plate 17 and pressure applied through linkage 20. The rod and spring assembly 32 was adjusted to apply a pressure of approximately five pounds per square inch on the overlapping portion of the filaments disposed between heater plate 17 and pressure plate 19. Each of the pairs of yarn were held against the heater plate over a distance of approximately one inch. Heater control means 18 was actuated, and heater bar 17 was brought to a temperature of approximately 200 C. The overlapping portion of the yarn ends softened and fused together. As the ends softened, the tension exerted by suction nozzle 22 caused the loose end portions to separate from the fused portions of yarn. On signal from the heater control assembly indicating that a predetermined time-temperature relationship had been achieved, pressure plate 19 was moved away from heater plate 17. A uniformly welded continuous warp of yarns was obtained, and the stretching operation resumed.

Various modifications of the apparatus of this invention will be apparent to those skilled in the art. For example, the particular configuration of the elements in the embodiment illustrated may be varied to accommodate other types of tensioning devices and heating means. In an alternative embodiment of the apparatus, the yarn ends are collected in a suction device and are secured under uniform tension on anchor rods positioned at the side of the frame. fore the yarns have cooled and solidified, the free ends may be separated from the fused yarns. Other modifications of the tensioning device which place the ends under substantially uniform tension during heat sealing and remove the free ends after the ends are fused may be used. For example, it may be advantageous when a large number of ends are being joined to position vacuum nozzles at both ends of the comb assembly to facilitate collecting and uniformly tensioning the ends. The heating means may be selected from a number of known types of apparatus, in addition to resistance heaters. For example, a dielectric heater may be advantageously used. The heater plate in the particular embodiment illustrated may, of course, be displaced either above or below the path of the yarns. In addition, other suitable means for displacing the pressure members toward and away from each other as well as means for adjusting the pressure may be used.

Materials used for construction apparatus of the type illustrated are well known. In general, those portions of the apparatus in which the yarns come in contact should be fabricated from abrasion-resistant materials. One or both of the pressure members may be coated with a material such as a polytetrafluoroethylene resin to prevent sticking of the yarns. The insulating material surrounding the heated member may be asbestos, mica, or a similar insulating material.

The apparatus and process of the present invention are useful in providing continuous warp sheets prepared from yarns selected from a variety of materials. In general, any thermoplastic yarn which can be heat sealed may be used, e.g., polyamides, polyesters, solvent-containing polyacrylics, polyhydrocarbons, etc. In some instances the use of an adhesive applied to the yarn ends may be required.

In joining the ends the temperature used must, of course, be controlled to prevent degradation or excessive flowing of the material. The optimum temperature and the time of heating can be readily determined by those skilled in the art. The optimum combination of temperature, time and pressure will, of course, vary depending on the nature of the material being processed, e.g., the polymeric structure, solvent or plasticizer content of the material and denier. For acrylic fibers such as acrylonitrile fibers containing 20-25% of the spinning solvent, temperatures in the range of 175 C. to 230 C. and pressures of five to twenty pounds per square inch have been found to be satisfactory.

Many advantages accrue from utilizing the process and apparatus of this invention. A plurality of yarn ends can be joined in a minimum amount of time as compared to that required for knotting individual ends. The resulting junctions are smaller in diameter than the knots and in many instances are actually stronger. In addition, the problem of severing loose ends is obviated. The process is particularly useful in joining fibers which are weak or brittle and would cause diificulty in tying knots therein.

It will be apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore it is not intended to be limited except as indicated in the appended claims.

I claim:

1. Apparatus for forming a plurality of continuous thermoplastic yarns from two separate warps comprising in combination a pair of pressure members having opposed flat pressure faces, a comb member displaced on each side of said pressure members for aligning the run- 1 out ends of one of said warps in essentially parallel over- After the heat-sealing cycle but belapping relationship with the lead-in ends of the other warp in a zone between said pressure members, tension means for receiving, engaging, and applying a constant tension to the terminal portions of said ends positioned adjacent to said pressure members, means for displacing said pressure members toward each other to compress the overlapping portions of said yarns interposed between said faces, and heating means for heating said overlapping portions to a heat-sealing temperature.

2. Apparatus for heat sealing a plurality of thermoplastic yarns of a first and second warp to form a continuous warp sheet comprising in combination a pair of pressure members having opposed fiat pressure faces, a comb member displaced on each side of said pressure members, a plurality of teeth in said comb members positioned to maintain the lead-in ends of the yarns of the first warp and the run-out ends of the yarns of a second warp in essentially parallel overlapping relationship in a zone between said pressure members, vacuum means positioned adjacent to said pressure members to receive the terminal portions of said ends and maintain said yarns under substantially uniform tension sufiicient to take up slack in the yarns before sealing and to remove said terminal portions after sealing, means for displacing said pressure members toward each other to compress the overlapping portions of said yarns interposed between said faces, and heating means for heating said overlapping portions to a heat-sealing temperature and softening the yarns so that the terminal portions may be detached and removed by said vacuum means.

3. Apparatus for heat sealing a plurality of thermoplastic yarns of a first and second warp to form a continuous warp sheet comprising in combination a pair of pressure members having opposed fiat pressure faces, a comb member displaced on each side of said pressure members, a plurality of vertical pins in said comb members positioned to maintain a portion of the lead-in ends of the yarns of said first warp and a portion of the runout ends of said second warp in essentially parallel overlapping relationship in a zone between said pressure members, a suction nozzle positioned beneath said pressure members to receive the terminal portions of said ends and to maintain said yarns under substantially uniform tension sutficient to take up any slack in said yarns prior to sealing and to detach and remove said terminal portions after sealing, means for displacing said pressure members toward each other to compress the over lapping portions of said yarns interposed between said faces, and heating means for heating at least one of said pressure members to a heat-sealing temperature.

4. Apparatus for forming a continuous warp sheet from two separate warps of thermoplastic yarns comprising in combination a pair of pressure members having opposed flat pressure faces, the first of said pressure members being fixedly positioned on a frame, a comb member positioned on said frame and displaced on each side of said first pressure member, a plurality of vertical pins extending upwardly from said comb member, said pins being positioned to maintain the lead-in ends of yarns of said first warp and the run-out ends of yarns of said second warp in essentially parallel overlapping relationship across said first pressure member, a suction nozzle positioned beneath said first pressure member shaped to receive the terminal portions of said ends and maintain said yarns under substantially uniform tension suflicient to take up slack in said yarns prior to sealing and remove said terminal ends after sealing, means for displacing the other of said pressure members toward said first pressure member to compress the overlapping portions of said yarns interposed between said faces, and heating means connected to said first pressure member for heating it to a heat-sealing temperature.

5. Process for forming a plurality of continuous thermoplastic yarns by joining together individual ends from two separate warps which comprises positioning a portion of the yarns of a first warp in overlapping relationship to a portion of the yarns of a second warp, applying an essentially equal tension to the loose ends of said portions while maintaining said overlapping relationship along said portions of said yarns, applying pressure to at least a part of the said overlapping portions, and thereafter heating said overlapping portions to a temperature whereby said filaments soften and fuse together, said tension being sufiicient to separate the loose ends from said overlapping portions when said yarns soften.

6. Process for forming a continuous warp sheet from a plurality of thermoplastic yarns of a first and second warp which comprises positioning a portion of the run-out yarns of said first warp in overlapping relationship to a portion of the lead-in yarns of said second warp, applying an essentially uniform tension to the terminal portions of said yarns to remove slack while maintaining said overlapping relationship along at least a portion of said yarns, applying pressure to said overlapping portions of said ends sufiicient to hold them in position, and thereafter heating said overlapping portions to a heat-sealing temperature, said temperature and said tension being controlled to separate the terminal portions of said ends from said overlapping portions after said yarns are sealed together.

7. The process of claim 6 wherein said yarns are comprised of acrylonitrile polymer.

8. The process of claim 7 wherein said temperature is between about C. and about 230 C., and said pressurle1 is between about five and twenty pounds per square 111C 9. An improved apparatus for simultaneously bonding a first group of separate yarns to a second group of separate yarns and trimming off all excess yarn end lengths, said apparatus comprising, in combination, a supporting frame structure, a pair of parallel comb members mounted on said structure and spaced a given distance apart, each comb member comprising a row of spaced parallel pin elements aligned with the set of corresponding parallel pin elements on said other spaced member, each aligned pair of pins on said comb members forming a yarn supporting and aligning arrangement for holding a yarn of said first group in parallel overlapping engagement with a yarn of said second group for a portion of their lengths, movable press means mounted on said structure constructed and arranged to engage and apply pressure to said overlapping portions of said yarns between said comb members, heating means operatively associated with said press means to apply sufficient heat in conjunction with the pressure on said overlapping portions of said yarns to bond the overlapping portions permanently together, a constant tension device positioned on said structure adjacent said comb members for engaging and exerting a constant tension on the loose end portions of said overlapped yarns to first insure a uniform bonding action in each laterally spaced pair of overlapping yarns between said comb members without slack in the overlapped bonded yarns and secondly to detach said loose end portions upon their separation from the bonded overlapping portions of the yarn under the softening action of the heat applied during the bonding operation.

10. The improved apparatus of claim 9 in which said constant tension device comprises an air suction nozzle.

11. An improved process for bonding together a runout yarn to feed-in yarn, said process comprising, in combination, the steps of aligning and supporting a portion of the length of the run-out yarn in parallel engagement with a portion of the length of the feed-in yarn, applying a constant tension to the loose run-out end of one yarn and the lose feed-in end of the other to eliminate slack, applying sufficient heat and pressure to said parallel engaged portions of the yarn to permanently bond them together while continuing to maintain tension on the ends of the yarn at a sufficient level to detach the loose end portions from the bonded engaged portions when the heat has sufliciently softened the yarns.

References Cited in the file of this patent UNITED STATES PATENTS 

1. APPARATUS FOR FORMING A PLURALITY OF CONTINUOUS THERMOPLASTIC YARNS FROM TWO SEPARATE WRAPS COMPRISING IN COMBINATION A PAIR OF PRESSURE MEMBERS HAVING OPPOSED FLAT PRESSURE FACES, A COMB MEMBER DISPLACED ON EACH SIDE OF SAID PRESSURE MEMBERS FOR ALIGNING THE RUNOUT ENDS OF ONE OF SAID WRAPS IN ESSENTIALLY PARALLEL OVERLAPPING RELATIONSHIP WITH THE LEAD-IN ENDS OF THE OTHER WRAP IN A ZONE BETWEEN SAID PRESSURE MEMBERS, TENSION MEANS FOR RECEIVING, ENGAGING, AND APPLYING A CONSTANT TENSION TO THE TERMINAL PORTIONS OF SAID ENDS POSITIONED ADJACENT TO SAID PRESSURE MEMBERS, MEANS FOR DISPLACING SAID PRESSURE MEMBERS TOWARD EACH OTHE TO COMPRESS THE OVERLAPPING PORTIONS OF SAID YARNS INTERPOSED BETWEEN SAID FACES, AND HEATING MEAND FOR HEATING SAID OVERLAPPING PORTIONS TO A HEAT-SEALING TEMPERATURE. 